License Plate Reader Technology | Automatic License Plate Reader

An Automatic License Plate Reader (ALPR) is an image-processing technology used to identify vehicles by their license plates.

It is a special form of OCR (Optical Character Recognition) where algorithms are employed to transform the pixels of the digital image into the text of the number plate Systems commonly use infrared lighting to allow the camera to take the picture at any time of day.

There are many applications for License Plate Readers such as traffic and parking management, tollbooth operations and area-access control. One of the fastest growing applications is the deployment of ALPR systems by law enforcement agencies across the country to identify persons or vehicles whose license plates are connected to a crime or infraction. Cameras, mounted to police vehicles or stationary structures such as gates or bridges, automatically take photos of license plates at the rate of hundreds per minute. The characters in the photo of the plate are then translated into letters and numbers and compared to law enforcement databases of registered vehicles known to be or suspected of being involved with crimes or infractions. If a license plate that was read matches an entry on a database, the license plate reader system will alert the officer (if the ALPR system is mounted to a police vehicle) or command center (if data is transferred to a remote management facility) that a suspect vehicle is in the immediate area of that ALPR system.

License plate recognition systems utilize algorithms in order to identify a license plate, take a clear image, translate its characters and identify the state that issued the plate. The better the algorithms, the more accurate the information.

Generally speaking, License Plate Readers (ALPRs) can record plates at about one per second at speeds of up to 100 MPH and they often utilize infrared cameras for clarity and to facilitate reading at any time of day or night. The data collected can either be processed in real-time, at the site of the read, or it can be transmitted to remote center and processed at a later time.